Rolling disk bit



1933- q. A. ZUBLIN 2,126,079

ROLLING DISK BIT Filed Jan. 24, 1938 Arroelvsv Patented Aug. 9, 1938 UNITED, STATES PATENT OFFICE 12 Claim.

This invention relates to drilling tools, and more particularly to that class of tools that is used in the rotary drilling of wells, and still more specifically to the type of drilling tool described in my United States Patents Nos. 2,050,988, 2,050,989, 2,069,795, 2,069,796, 2,069,797, 2,069,798, 2,069,799, and 2,079,142.

Hard formations can best be removed by being broken up, as distinguished from their removal by a scraping action. But for the formation to be broken it is necessary that the cutters l6 tively high drilling weights, which are necessarybecause of the relatively large number of roller teeth with a correspondingly large surface in contact with the formation. A decreasing of the area of the cutters in formation contact would increase the extent of penetration for the same drilling weight and would thereby permit the formation to be removed more readily.

Accordingly it becomes an object of this invention to provide a drilling bit capable of penetrating a formation under relatively light drilling weights.

A further object of the invention lies in the provision of a bit having continuous rolling motion on the formation while in contact therewith.

Still another object of the invention concerns a drill bit which can effectively. penetrate hard and" tough formations that are difficult to drill. but which can be removed by being broken away. 1 Another object of the invention resides in the 95 provision of a bit having disk cutters rollable on the formation to produce a criss-cross narrow groove pattern thereon, thus facilitating and causing its breakdown.

, Still another object of the invention is to pro- 0 vide a bit having disk cutters in which each cutter can cross its own path when in rolling contact with the formation.

A further object of the invention is to provide a bit including disk cutters having a self-sharpen- 95 ing efl'ect by virtue of their penetration in the formation.

How these objects and others are obtainable will be understood by reference to the following description and the annexed drawing, in which:

50 Figure 1 is a partial section on the line l-i of Figure 2;

Figure 2 is a partial section on the line 22 of Figure 1: and

Figure 3 is a longitudinal section through a hole produced by the drill bit shown in Figures 1 and 2, illustrating the pattern formed by the cutters on the hemispherical hole bottom.

In its general aspects, the invention contemplates the use of rolling disk cutters which produce a breakdown of the formation. In the prior art drill bits using disks, the cutting edges thereof remove the formation by a scraping action, similarly to the action of a drag bit, the disks rotating about their own respective axes to present a greater extent of scraping surface to the formation than is obtainable by the use of a drag bit. Because of the scraping 'action, the edges of such disks are readily blunted impeding further progress of the drilling tool in making a hole. In contradistinction to the scraping action of the known disk bits, I have provided a. drilling tool using disk cutters having substantially a rolling action on the formation, cutting many narrow grooves, closely spaced together, leaving narrow ridges of formation that break off readily for subsequent removal by the drilling fluid. While producing the narrow grooves, sliding action of the sides of the grooves along the cutting edges of the disks will self-sharpen them and therefore permit them tomaintain an efiicient edge for penetrationinto the formation.

The specific drilling tool disclosed on the drawing is of the general type described in my prior patents, above referred to, and particularly in Patents Nos. 2,069,799 and 2,079,142. The drill bit is provided with a shank I0 having on its upper end a threaded portion il by means of which the shank is attached to a drilling string for rotation about a generally longitudinal ,axis AA. The lower portion of the shank is providedwith two depending legs i2 carrying between th m a cutter carrier it. About the periphery of the cutter carrier is' rotatably mounted a plurality of roller disk cutters ll. As described in Patent No. 2,079,142, the carrier is rotatably mounted between the shank legs by means of bearing member I! which consists of a central cylindrical sleeve l6 and flanges i I screwed into each end of the bearing sleeve. The carrier has an inner cylindrical surface it rotatably mounted on the sleeve, and inclined surfaces l8 complementary to the flanges. Between the flanges and these inclined surfaces are ball bearings 20 which serve to transmit part of the radial load on the carrier and all. of the axially parallel loads.

On the vided a raised boss Ziwhich is inserted into a transverse slot .22 in each of the legs of the shank. The bosses are flattened across their outer surface of each flange is protop and bottom sides 23, 24 in order that they can be slid into the slots in the legs and be held from rotating relatively thereto. Relative rotation between the flanges is prevented by means of a locking pin 25. The entire bearing assembly is attached to the legs of theshank and held in proper position by tapered pins 26 which are externally threaded at 21, cooperating threads being supplied in each flange. Removal of the tapered pins is prevented by inserting cotter keys 28 through a. bore 29 in each pin, the legs of each key being bent back to engage with castellations 30 in each pin and with slots 3| in the shank.

To lubricate the bearing surface, passageways 32 for the circulating fluid are supplied at intervals around the carrier. These passageways will convey the fluid from each roller cutter to the bearing surface.

The drill bit is kept free from cuttings by means of a nozzle 34 threaded into the shank and communicating with the fluid passage 33 contained therein. The fluid stream issuing from this nozzle will engage against the roller cutters to cleanse them of adhering matter and will also rotate each cutter about itsown axis so as to present all edges of the cutters to the action of the fluid stream. It will be noted that the nozzle is inclined in the direction of rotation of the carrier so that the fluid stream will act against the sides 35 of the carrier defining the slots 36 in which the disk cutters are mounted and exert a force causing carrier rotation. Because of the fact that the carrier rotates, all of the cutters will be successively positioned under the nozzle so that it can clean all of them and the cutting edges of each of them effectively.

As explained in my Patents Nos. 2,050,98 8 and 2,069,799, a drilling tool of the type just described will have its cutters brought intermittently into and out of contact with the formation being operated upon. Thus, each cutter has three degrees of freedom of motionname- 1y, revolution about the axis A-A of the hole, revolution about the inclined axis 3-3 of the carrier, and rotation about its own axis, which is the axis of the pins 31 directly supporting each cutter. In view of the three degrees of freedom of motion aforementioned, each cutter will trace a generally spiral path upon a concave or hemispherical bottom of the hole produced by drill bits of this type. The cutters moving from the bottommost portion of the hole upwardly thereof will move in an outward spiral while the cutters moving downwardly along the hemispherical hole bottom will move in-an inward spiral.

The spiral paths are exemplified in Figure 3 in which the cylindrical hole portion 38 is shown as terminating in the concave or hemispherical bottom 39. The disk cutters M, as they roll around on the bottom will trace the paths designated by the lines Illa and 4017, the former illustrating pathsthat are traced as the cutters most portion of the hole. Thus, the upwardly moving cutters penetrate the formation to form generally parallel spiral grooves leaving ridges II of formation between them which will readily break off. The downwardly moving cutters will do likewise. Although the paths traced on Figure 3 show the ridges to be rather wide, it is to be understood that in actual operation the generally parallel lines are more numerous and are much closer together leaving a rather narrow ridge which is incapable of sustaining itself aflixed to the formation.

The disks will cut a relatively deep groove into the formation which will permit the ridged portions to break off more readily than if a shallower groove were cut. This will enhance the rate of drilling, although, of course, even a slight penetration would result in the breaking of the formation. The breakdown is further accelerated and assisted by reason of the fact that the upwardly directed and downwardly directed spiral grooves cross each other leaving isolated diamond shaped areas having a lesser extent of attachment to the formation than a continuous ridge formed by adjacent substantially parallel grooves would have. The cutters will penetrate the formation to produce the cries-cross pattern illustrated, and in addition, the drilling bit exemplifying the present invention possesses the property that each disk will move on an outward spiral upon moving upwardly and on an inward spiral upon moving downwardly. The effect is that eachdisk cutter will cut a groove as designated by the lines 40a in moving upwardly and a groove 40b while moving downwardly. In other words, each cutter is capable of crossing a pre-existing groove formed by it, and consequently, tracking is eliminated, so long as the cutter carrier rotates about its axis, as the inclined axis BB.

As distinguished from the action of roller cutters having teeth, which will deliver repeated impact blows in an attempt to break through the formation, disks maintain continuous contact with the hole bottom breaking through the formation by virtue of continued and progressive effort rather than by a series of blows. In this manner, the resiliency of the formation is overcome and the generally parallel grooves produced to isolate the particles of formation in the manner aforementioned. In further contrast with the use of. tooth roller cutters, the disks have much smaller area in contact with the formation so that the same drilling weight will provide a much greater unit pressure forcing the cutting edges of the disks into the earth and forming the multitudinous series of grooves which are so effective in making drilling progress.

In general, disks have been used heretofore for hard formation drilling but they are necessarily of relatively large diameter presenting a large area to the formation and consequently requiring high drilling weights in effecting formation penetration. My invention preferably contemplates the use of relatively small rollers so that a greater extent of penetration will occur inasmuch as a lesser circumferential length of cutter surface is engaged with the sides of the grooves. The use of small disks and the fact that increased penetration is obtainable with them renders it feasible to provide a number of on each roller results in a much larger extent of cutting edge that-can operate upon 'the' formation, and as a result-increases the effective life of the drilling tool. In general, it can be stated that the diameter of the disks should be less than one-third of the diameter of the hole.

The use 'Of disk bits in connection with the perpendicular to the carrier axis 3-H and with the central planes of each set of disks including a radius of the hemisphere. Furthermore, due to the manner of mounting. the disks on the car-- rier, they will make substantially the same radial angle of contact with the hemispherical hole bottom regardless of their specific contacting position with the formation. With the specific arrangement of parts disclosed, a disk radius drawn to its point of contact will be perpendicular to the carrier axis. in each set illustrated could be replaced by its full equivalent of a single roller having the same number of disks and of the same axial extent without affecting the transmissio'rfof the thrusts or the smooth operation of the bit, or each disk shown could constitute an individual roller.

The pins 31 upon which the disk cutters are mounted are shown as lying in a plane perpendicular to the inclined axis 3-3 of the carrier. With the carrier mounted to rotate with respect to the shank about an inclined axis, the perpendicular arrangement shown will provide a substantially pure rolling motion of the cutters over a major portion of the formation, as well as the type of thrust transmission and contact previously described. However, it is not essential for an operative bit that the carrier be inclined. For example, it can be mounted with its axis perpendicular to the shank axis as illustrated in my Patents Nos. 2,056,988, 2,050,989, and in most of my other United States patents previously mentioned'. With the end in view of still providing substantially pure rolling motion upon the major portion of the formation, it might be advisable to incline the pins 31, as designated in Figure '1 of my Patent No. 2,050,988. That is, the end of the pin 31 carrying the lowermost disk roller shown in Figure 2 of the instant application would be positioned forwardly in the direction of the rotation of the shank, with its other end trailing. Such change might be made with the inclined carrier construction presently shown if the bit were to be run in formations in which a combined rolling. and scraping action would be desirable for producing speedy removal of the particular formation.

Because of the narrow grooves that are cut by the disks as they roll on the bottom they will be self-sharpened by reason of the sides of the grooves rubbing against the inclined faces of each disk. By maintaining each disk with a sharp edge during its entire useful life a high unit formation penetration pressure will be maintained to correspondingly continue a high rate of drilling progress even while the parts become otherwise worn.

It will be understood that my invention may be embodied in various forms and that the specific illustration on the drawing is to be construed as an example of the invention rather than as im-.

For that matter, the pair of rollers parting any limitations thereon: and that various changes can be made without departing from the invention so long as they fall within the scope of the claims appended hereto.

I claim:

1. An earth boring tool comprising a shank, one or more disk cutters rotatable with respect to said shank, each cutter having one or more continuous circumferential cutting edges, and means mounting said cutters on said shank for successive intermittent contact with the formation.

2. An earth boring tool comprising a shank, one or more disk cutters rotatable with respect to said shank, each cutter having one or more continuous circumferential cutting edges, and means mounting said cutters on said shank for rolling motion on the formation in paths having a variable distance from the axis of the bore.

3. An earth boring tool comprising a shank, one or more disk cutters rotatable with respect to said shank, each cutter having one or more continuous circumferential cutting edges, and means mounting said cutters on said shank for rolling motion in generally spiral paths on the formation.

4. An earth boring tool comprising a shank, one or more disk cutters rotatable with respect to said shank, each cutter having one or more continuous circumferential cutting edges, and means mounting said cutters on said shank for rolling motion in generally spiral paths on the formation, said means including instrurnentalities for causing said cutters to intermittently contact with the formation.

5. An earth boring tool comprising a shank, a disk cutter rotatable with respect to said shank, said cutter having a continuous circumferential cutting edge, and means mounting said cutter on said shank for rolling motion on the formation alternating between outwardly and inwardly directed generally spiral paths traced thereon.

6. An earth boring tool as defined in claim 5, wherein the outwardly and inwardly directed generally spiral paths cross each other.

7. An earth boring tool comprising a shank; a cutter carrier rotatably mounted on said shank; and a plurality of cutters, each having one or more continuous circumferential cutting edges, mounted on said carrier for successive intermittent contact with the formation.

B. An earth boring tool comprising a shank, a cutter carrier rotatably mounted on said shank, and a plurality of disk cutters mounted onsaid carrier for successive intermittent contact with the formation, each cutter having one or more continuous circumferential cutting edges, the diameter of each disk being less than one-third of the diameter of the bore.

9. An earth boring tool comprising a shank, a cutter carrier rotatably mounted on said shank, and a plurality of disk cutters mounted on said carrier for successive intermittent contact with the formation, each cutter having one or more continuous circumferential cutting edges, the cutters being spaced around the carrier to produce a substantially hemispherical bottom in the formation.

10. An earth boring tool comprising a shank, a cutter carrier rotatably mounted on said shank, and a plurality of disk cutters mounted on said carrier for contact with the formation, each cutter having one or more continuous circumferential cutting edges, thecutters being spaced around the carrier to produce a substantially heinispherical bottom in the formation, a cutter radius drawn to its point of'formation contact maintaining a constant angle with the formation bottom as the carrier rotates.

11. An earth boring tool comprising a shank, a cutter carrier rotatably mounted on said shank,

and a plurality of disk cutters mounted on said center of the hemispherical bottom for all 12. An earth boring tool comprising a shank, a cutter carrier rotatably mounted on said shank, and a plurality of disk cutters mounted on said carrier for contact with the formation, each cutter having one or more continuous circumfer-.

ential cutting edges, the cutters being spaced around the carrier to produce. a substantially hemispherical bottom in the formation, the central planes of said cutters passing through the time of rotation of said carrier.

' Join: A. zumm.

posi- 10 

